Anaerobic transformation of organosulfur compounds in microbial mats from octopus spring

Hot spring microbial mats formed in the vicinity of Octopus Spring, Yellowstone National Park, Montana, were examined for the anaerobic transformation of organosulfur compounds. When oxygen was excluded, slurries made with mat material emitted hydrogen sulfide, methanethiol, dimethyl sulfide, and dimethyl disulflde. When added to slurries, cysteine and glutathione acted as precursors for hydrogen sulfide. Hydrogen sulfide concentrations in the headspace were doubled in the presence of these compounds. Methionine served as a precursor for methanethiol, while dimethylsulfoniopropionate (DMSP) was determined to be a precursor for dimethyl sulfide. Headspace concentrations of methanethiol were greatly increased by the addition of methionine and slightly enhanced by the addition of glutathione, cysteine, or DMSP. Dimethyl sulfide formation was enhanced by the addition of DMSP to the slurries. Only a slight increase in dimethyl sulfide was observed in vials amended with methionine, glutathione, or cysteine. The...